Proximity sensors are conventionally used to detect the presence of an object without any physical contact. A typical proximity sensor comprises a light source to emit light and a photo detector to detect light reflected by an object that is within a predetermined proximity of the sensor.
Proximity sensors have been widely used in many devices and also for many industrial applications. For example, in an automated production assembly line, proximity sensors are used to detect the position of a machine component in the production line and also for counting of parts produced by a production tool. Whereas in the robotics industry; the proximity sensor may be used to monitor a robot's position and control the movements of the robot. The proximity sensor is also commonly used as an electronic switch to open and close an electrical circuit when an object is detected by the sensor. More recently, optical proximity sensors have been widely employed in portable electronic devices, such as a portable handheld device, mobile phone and portable computers.
In general, a proximity sensor comprises an invisible light source and a photo detector. When an object comes within a predetermined distance of the sensor, the object reflects the light from the light source toward the photo detector. After sensing the reflected light, the photo detector subsequently sends an output signal, indicating the presence of an object. Typically, an action is performed in response to the output signal, such as turning on water, opening a door, etc. Thus, the conventional proximity sensors are utilized merely to facilitate the detection of an object within a predetermined proximity of the sensor. Despite the ability to detect objects without any physical contact, conventional proximity sensors provide only heretofore been utilized for object detection in either the horizontal or vertical direction of a plane parallel to the top surface of the proximity sensor. Thus, the use of proximity sensors in electronic devices has heretofore been limited to merely performing single plane object detection.
In conventional design, in order to provide movement detection or an X-Y direction motion sensing function to a proximity sensing device, a dedicated X-Y motion detecting device has to be integrated along with a proximity sensor. As a result, this increases the cost and also the overall size of the device because more space is needed to accommodate two separate systems. Accordingly, it would be desirable to provide a single device or system that is functionally capable of providing proximity sensing operations, an X-Y directions motion sensing operations as well as being able to provide multi-directional movement detection.